Might want to just try a high quality conference speakerphone. They have advanced audio processing, directional microphones, noise cancellation, etc. built in - since they are designed for this kind of audio from the ground up.

You can find the Konftel Ego for $80 at Provantage.com (around $120 everywhere else). Konftel makes amazing speakerphones that rival polycomm, for a lot less. Indeed, I actually prefer their sound to polycomm.

The Ego will be a dramatic upgrade from whatever is built into your other gear. If you still aren't happy with it, then you can start going down the USB/XLR microphone rathole if you still prefer. But it's probably unnecessary.

There are a ton of guides online, especially since the pandemic started. Getting a USB microphone is so easy and cheap that you probably don't need a guide for it. The guides that I've seen for USB mics are generally focused on the features that streamers need, which are somewhat unique (they want to capture desktop audio at the same time).

If you are going for the prosumer option, I recommend Scarlett Solo + Shure SM58 + XLR cable + mic stand. This may be a bit overkill for meetings, but it's a good starting point if you want to record music, stream, record a podcast, etc.